Method of making a stiffened fabric



Patented Sept. 26, 1939 UNITED STATES 2,173,821. METHOD or MAKING A STIFFENED FABRIC Bjorn Andersen, Maplewood, N. J., assignor to Celluloid Corporation, a corporation of New Jersey No Drawing. Application-May 5, 1936,

Serial No. 77,916,

9 Claims.

This invention relates to the manufacture of stiffened articles and more particularly to the manufacture of box toes for shoes employing as the stiiienlng material a fabric impregnated with I a derivative of cellulose.

An object of the invention is the economic and expeditious production of stiffened articles such as counters, box toes, inner soles and other parts of shoes and like objects. Another object of the invention is the production of stiffening material which more readily and more uniformly adheres to the surface and lining layers of the article in which the stiffening material is used. Other objects of the invention will appear from the following detailed description. I

The manufacture of box toes or shoe stifieners is generally carried out by precipitating a cellulose derivative in the form of fine particles in the interstices of a cloth or other sheet material. After the cloth has been impregnated with the cellulose derivative and allowed to dry, blanks of convenient shape and size are cut out by the shoe manufacturer. These blanks are i then dipped for a very short time in a solvent bath, the strength of which is carefully regulated to impart the desired degree of gelatinization and pliability. For the purpose of describing this invention and in the appended claims this solvent bath will be referred to as the softening solution.

30 While in this flaccid and swollen condition, the

blanks are cemented or laminated between an inher -cloth lining and "the outside leather layer.

The reinforced composite is then shaped over a wooden last to the contour of the shoe and the solvents allowed to volatilize, with the formation of a stiiiened form.

I have discovered a unique method of insuririg a very intimate and uniform adhesion between the stiffening material and the contacting layers. 40 This method comprises adding to the solvent bath in which the blanks are dipped an agent, preferably a base such as ammonia, which dissolves or cuts into the usual finishes on the inner fabric F lining and leather outer layer and/or otherwise causes the stiffening material to readily seize and adhere to said contacting layers. It is very important for efficient hand or mechanical operaprior to reaching to the last. If the stiffening material does not readily seize onto the lining and leather, it greatly slows up production since it necessitates a longer and more strenuous pressing together of the layers. Where shoes having cut- 5 out decorations are being formed, heavy pressing must be avoided as this causes the plastic material to be pushed into the cut-out portions.

In accordance, with my invention, I employ, in the manufacture of stiffened articles contain- 0 ing a sheet material comprising a base sheet impregnated with a derivative of cellulose as the stiffening member, a softening solution which renders the stiffening member soft, adhesive and moldable. The softening solution comprises a w solvent for the derivative of cellulose employed and an agent that cause the softened stiffening member to seize and adhere to other sheet material. The solvent may be any suitable reagent or mixture of reagents having a solvent action upon the derivative of cellulose, While the added agent may be any agent that causes the softened 3 material to seize and adhere to other sheet material, such agents may be water, an organic acid or, more preferably, an inorganic basic compound such as ammonia.

This invention is applicable to the formation of stiffened articles such as box toes, counters,

inner soles, etc. of shoes, belts, supports, collars and like wearing apparel and also to industrial articles such as cases for technical instruments, sheaths for cutting instruments, caps for breeches of field artillery, etc. The outer layer,

in most cases named above, will be leather while the inner layer is of varying weights of muslin.

However, this invention is not limited to such assemblies. For instance, any flexible or semiflexible sheet material may be employed as eitherthe lining layer or the outer layer. Examples of suitable sheetmater-ials for use as the lining or outer layers are leather, patent leather, imitation leather, fabrics of silk, cotton, wool, artificial fibres or filaments, felts, paper and the like.

The stiffening member or layer may be formed of any suitable base material impregnated with a derivative of cellulose. The base material may be any suitable cloth formed from cotton fibers,

- silk, animal fibers, artificial fibres and filaments,

etc. The base ,material may be impregnated with any suitable derivative of cellulose in any suitable manner. Examples of suitable derivatives of cellulose are cellulose nitrate, cellulose acetate, cellulose nitro-acetate, cellulose formate, cellulose propionate or other esters of cellulose. Celsoftening solutions containing ammohia, if

luloae ethers and the ether-esters of cellulose may also be employed such as cellulose aceto butyrate.

Blanks cut from the stiflening material are dipped for a very short time in a softening solution which rendeiis them soft and hand moldable.

when moistened with the softening solution, they low boiling solvent, there is formed, upon evaporation, a skin coating which is not adhesive. In accordance with this invention, I form a softening solution which overcomes the difficulties arising from lack of adhesion in the stiffening material by adding to the softening solution an agent which produces an adhesive property in the stiffening material. This agent is preferably an inorganic alkaline substance either {soluble in the softening solution or at least in onecomponent of the softening solution. Although sodium, potassium and other alkaline or alkaline earth metal hydroxides mayv be employed, I pre-- fer to employ, whenever possible, ammonium hydroxide owing to the volatile nature of the same. Organic base substances may ako be employed, such as triethyl amine, triphenyl aminejtriethanolamine, etc. These alkaline or basic substances are referred to in the claims as alkalis. I have also found that good adhesive properties may be imparted to the stiffening material by adding, in place of the alkaline or basic substance, a concentrated organic acid to the softening solution. Examples of suchorganic acids are formic acid, glacial acetic acid, etc. I may also employ a small amount-of water to effect the property of good adhesion.

The quantity of the agent, which produces an adhesive property in the stiffening material, added to the softening solution may vary from less than 0.5 to more than based on the volume of the softening solution. The quantity employed for best results will depend upon the particular agent employed. When employing acetone as the softening solution and cellulose acetate or cellulose nitrate as the derivative of cellulose in the stiffening material the amount of ammonium hydroxide (commercial grade of about 28% NHa) required to produce good adhesive properties is from 0.5 to 5% by volume. The

allowed to [stand until the characteristic odor of the ammonia has largely dissipated, are not impaired in softening and cementing qualities.

The softening solution may be formed of one or ,a mixture of low boiling solvents, with or without plasticizers and high boiling solvents for the particular derivative of cellulose employed in the stiffening material or sheet. Examples of suitable solvents for cellulose esters are acetone, methyl acetate, methyl cellosolve (mono methyl ether of ethylene glycol), cellosolve (mono ethyl ether of ethylene glycol), chloroform, ethylene dichloride, mixtures of ethyl or methyl alcohol and acetone, mixtures of ethylene dichloride and ethyl or methyl alcohol, etc. Examples of plasticizers that may be employed either in the derivative of cellulose impregnating material or in the softening solution are the aryl sulphonamides such as para ethyl toluol sulphonamide, the alkyl phthalates such at; dimethyl phthalate, the dialkyl tartrates such as dibutyl tartrate, the alkoxy esters of polybasic organic acids such as dlethoxy ethyl phthalate, the polybasic acid esters of the mono alkyl ethers of polyhydric alcohols,

such as diethylene glycol ethyl ether ester of phthalic acid, the alkyl ester of phosphoric acid such as triethylglycol phosphate, the aryl esters of phosphoric acid suchas tricresyl phosphate, the mixed alkyl and aryl phosphates such as ethylglycol dicresyl phosphate, and camphor.

The drying time or period of stickiness of the stifiening material may be varied by adding to the softening solution higher boiling solvents. Examples of suitable higher boiling solvents for nitrocellulose and cellulose acetate are methyl cellosolve, methyl cellosolve acetate, diacetone alcohol, benzyl alcohol, beta, beta dichlorethyl ether.

Examples 'of softening solutions particularly applicable to cellulose acetate box toe material' are:

quantity of alkaline or other agent may be reduced to below 0.5% by volume.

The addition of'the alkaline agent to the softening solution not only gives to the treated Example! Parts by volume Methyl acetate 100 6,8 dichlorethyl ether 5 Commercial ammonium hydroxide 4 Example If Parts by volume Acetone 100 ,3 B dichlorethyl ether 10 Methyl cellosolve acetate 10 Commercial ammonium hydroxide 3 Example III Parts by volume Methyl cellosolve 80 Diacetone alcohol 15 Glacial acetic acid 5 Example IV Parts by volume Methyl aceta 50 Diacetone alcohol 50 40 Methyl cellosolve acetate 100 Benzyl alcohol 50 Ammonium hydroxide 3 An example of a suitable softening solution for nitrocellulose box toe material is:

EzampleV Parts by volume Acetone 65 Ethyl methyl ketone 8 Ethyl alc 8 Amyl acetate 40 Dimethyl phthalate 8 Ammonium hydroxide 1 Example VI Parts by volume Methyl acetate 100 Methyl cellosolve 25 Water, 5

Example VII Parts by volume Methyl acetate 100 Methyl cellosolve 75 Methyl cellosolve acetate .75 Water 5 When high boiling solvents are-added to .the softening solution the amount of agent producing an adhesive property in the stiffening material may be reduced. In s'ome'formulas the material an'adhesive property but also acts to without departing from the spirit of my invention.

Having described my invention, what I desire to secure by Letters Patent is:

1. A softening solution for use in rendering moldable a stiffening material containing a derivative of cellulose, comprising a low boiling solvent for the derivative of cellulose and an alkali which has a softening action on the material of the article to which the stiffening material is to be applied.

2. A softening solution for use in rendering moldable a stiffening material containing an ester of cellulose, comprising a low boiling solvent for the ester of cellulose and an alkali which has a softening action on the material of the article to which the stiffening material is to be applied.

3. A softening solution for use in rendering moldable a stiffening material containing a de rivative of cellulose, comprising a low boiling solvent for the derivative of cellulose and aqua ammonia which has a softening action on the material of the article'to which the stiffening material is to be applied.

4. A softening solution for use in rendering moldable a stiffening material containing an ester lose and an alkali which has a softening action on said outer layer, shaping the treated article and drying the same.

6. In a method of stiffening toes of shoes and other articles by the use of a stiffening material containing an ester of cellulose, the steps of applying to an article comprising-an outer layer and the stiffening material a softening solution containing a solvent for the ester of cellulose I and an alkali which has a softening action on said outer layer, shaping the treated article and drying the same.

'7. In a method of stiffening toes of shoes and other articles by the use of a stiffening material containing a derivative of cellulose, the steps of applying to an article comprising an outer layer and the stiffening material a softening solution containing a solvent for the derivative of cellulose and a small amount of aqua ammonia which has a softening action on said outer layer, shaping the treated article and drying the same.

8. In a method of stiffening toes of shoes and other articles by the use of a stiffening material containing an ester of cellulose, the steps ofapplying to an article comprising an outer layer and the stiffening material a softening solution containing a solvent for the ester of cellulose and a small amount of aqua ammonia which has a softening action on said outer layer, shaping the treated article and drying the same? 9. In a method of stiffening toes of shoes and other articles by the use of a stiffening material containing a derivative of cellulose, the steps of applying to an article comprising an outer layer and the stiffening material a softening solution containing a solvent for the derivative of cellulose and from .05 to 5% by volume of an alkali which has a softening action on said outer layer, shaping the treated article and drying the same.

BJORN ANDERSEN. 

